HerokuにPhantomJSをセットアップ[Heroku]

$ heroku config:add BUILDPACK_URL=https://github.com/ddollar/heroku-buildpack-multi.git
$ touch .buildpacks
$ echo "https://github.com/heroku/heroku-buildpack-python" >> .buildpacks
$ echo "https://github.com/stomita/heroku-buildpack-phantomjs" >> .buildpacks
$ git add --all
$ git commit -m "add phantomjs"
$ git push origin master
$ git push heroku master